Answer:
381 different types of pizza (assuming you can choose from 1 to 7 ingredients)
Step-by-step explanation:
We are going to assume that you can order your pizza with 1 to 7 ingredients.
So, in total you have 7 + 21 + 35 + 35 + 21 +7 + 1 = 127 ways of selecting ingredients.
But then you have 3 different options to order cheese, so you can combine each one of these 127 ways of selecting ingredients with a single, double or triple cheese in the crust.
Therefore you have 127 x 3 = 381 ways of combining your ingredients with the cheese crust.
Therefore, there are 381 different types of pizza.